Data commit

Task/Power-set/Lambdatalk/power-set.lambdatalk

@@ -0,0 +1,29 @@
+{def powerset
+
+{def powerset.r
+ {lambda {:ary :ps :i}
+  {if {= :i {A.length :ary}}
+   then :ps
+   else {powerset.r :ary
+                    {powerset.rr :ary :ps {A.length :ps} :i 0}
+                    {+ :i 1}} }}}
+
+{def powerset.rr
+ {lambda {:ary :ps :len :i :j}
+  {if {= :j :len}
+   then :ps
+   else {powerset.rr :ary
+                     {A.addlast! {A.concat {A.get :j :ps}
+                                           {A.new {A.get :i :ary}}}
+                                 :ps}
+                     :len
+                     :i
+                     {+ :j 1}} }}}
+
+ {lambda {:ary}
+  {A.new {powerset.r :ary {A.new {A.new}} 0}}}}
+
+-> powerset
+
+{powerset {A.new 1 2 3 4}}
+-> [[],[1],[2],[1,2],[3],[1,3],[2,3],[1,2,3],[4],[1,4],[2,4],[1,2,4],[3,4],[1,3,4],[2,3,4],[1,2,3,4]]]